20 mm

0.85λλλλo

Parallel-plate

structure

2λλλλp

0 100 200 300 400 500 600-180

-150

-120

-90

-60

-30

0

30

Ez

ph

ase [

deg]

Initial 1st iteration

Position of Feeder in direction [mm]

Coupling Slot

y

0 100 200 300 400 500 600 700-120

-90

-60

-30

0

30

60

90

120

Ex,E

y P

has

e [

deg

]

Position of Raditing Panel in direction [mm]

Ex phase (1st iteration)

Ex phase (Initial)

Ey phase (Initial)

Ey phase (1st iteration)

Radiating Slot

x

Short

��

� Hardwall

hw

Wp

Lp

Hardwall

zx

y

Lf

Antenna input

Parallel plate

Feeder

RHCP port

Satellite

Body

One Antenna Panel

(current design is RHCP)

Rectangular waveguide

feeder to each panel

[top view]

[bottom view]

Choke Flange

x

z

y

70 cm70 cm

LHCP port

xz

y

Parallel-Plate Slot Array Antenna for MicroXSAR Mission

† Institute of Space and Astronautical Science - Japan Aerospace Exploration Agency (ISAS - JAXA)‡ Tokyo Institute of Technology

AbstractRectangular parallel-plate slot array antenna fed by

rectangular waveguide at its bottom sides has been proposed.

This antenna will be implemented for dual polarized deployable

Synthetic Aperture Radar (SAR) antenna onboard 100 kg small

satellite. As to verify the possibility of the implementation of

this antenna, experiment on one antenna panel (about 700 mm x

700 mm) with right handed circularly polarized radiation has

been conducted. This paper describes the design of this one

antenna panel using simplified model in HFSS. Moreover, the

measurement results of the fabricated antenna will be

discussed. It is shown that 80 % aperture efficiency with the

directivity of 36.5 dBic and 55% antenna efficiency with the

gain of 34.9 dBic are achieved at 9.65 GHz as the targeted

center frequency.

Keywords : small SAR sensor, rectangular slot array antenna, X-

band antenna

Prilando Rizki Akbar††††,,,,Hirobumi Saito††††,,,, Miao Zhang ‡, Jiro Hirokawa ‡ and Makoto Ando ‡

References

1. M.iao Zhang, Jiro Hirokawa and Makoto Ando,

“Design of a partially-corporate feed double-layer

slotted waveguide array antenna in 39 GHz band and

fabrication by diffusion bonding of laminated thin

metal plates,” IEICE Trans. Commun., vol. E93-B,no.10, pp.2538-2544, Oct. 2010.

2. Tung Nguyen, Rushanthi J., K. Sakurai, J. Hirokawa,

M. Ando, M. S. Castaner, O. Amano, S. Koreeda, T.

Matsuzaki and Y. Kamata, “Propagation

characteristics of honeycomb structures used in mm-

wave radial laine slot antennas,” IEICE Trans.Commun, vol.E97-B, no.6, pp.1139-1147, June 2014.

3. Prilando Rizki Akbar, Hirobumi Saito, Miao Zhang,

Jiro Hirokawa and Makoto Ando, “Slot Array Antenna

for X-SAR onboard A Small Satellite,” in Proc. IEICEGeneral Conference, 2013, B-1-100.

P-279

x

z

y

Antenna panel

(parallel-plate slot

array antenna and

its rectangular

waveguide feeder)

Choke Flange

Satellite

body

xy

z

Upper Aluminum plate

Radiating slot

Honeycomb core

Adhesive sheet

Adhesive sheetLower Aluminum plate

ts

tg

tc

[Parallel Plate Structure]

60 80 100 120 140 160 180-2200

-2000

-1800

-1600

-1400

-1200

-1000

-800

-600P

hase

[d

eg]

Position from center [mm]

β = −11.92

60 80 100 120 140 160 180-2200

-2000

-1800

-1600

-1400

-1200

-1000

-800

-600P

hase

[d

eg]

Position from center [mm]

β = −11.92

W drection

[bird view]

Coupling slot

Inductive

wall

Feeder Parallel-plate

structure

��

�

b

a

[single coupling slot]

z

x

y

[top view]

Feeder

PBC

Input Port

Port 3

Port 2

il

i w

rs ip

γγγγ

sw

��

�PBC

sl

Inductive

wall

2��

z

y

x

z

y

x

Short

Input port

ds(n, n-1)

��

�

Hardwall

Hardwall

Coupling slot

Inductive wall

Impedance

boundary

Parallel-plate

structure

Feeder

n = 1

n = N

��

�

[Coupling slots at feeder of one antenna panel]

Input port

Short

ds

[Fabricated Feeder]

z

y

x

��

�

rl

sw

Rs

dx

dy

rl

135°°°°

45°°°°

Center of radiating

slot pair

[one radiating slot pair ]

xy

z

xy

z

Parallel-plate

structure

��

�

dr (m, m-1)

Radiation

boundary

m = 1

m = M

[1 dimensional array of radiating slot]

zy

x

Parameters Size (mm)

Parallel-plate (Wp x Lp)

Feeder Length (Lf)

Feeder inner size (a x b)

Inductive wall width, iwSlot width, swSlot round edge radius, rsHardwall width, hwThe thickness of

- Aluminum skin sheet, ts- Adhesive sheet, tg- Honeycomb core (SAH-1/4-1.5) , tc- Hardwall

- Feeder broad wall

657.2 x 700

678.4

22.86 x10.18

1

2

1

4.89

0.3

0.13

6

6.26

1

Item Mass (gram)

Upper parallel aluminum plate

Lower parallel aluminum plate

Honeycomb core sheet

Adhesive sheet

Hard Surface wall

Aluminum Frame

Feeder waveguide

Total antenna system

344

358

65

138

57

24

162

1148

-90 -60 -30 0 30 60 90-50

-40

-30

-20

-10

0

YZ Plane

Angle [deg]

No

rmal

ized

Rad

iati

on

Pat

tern

[d

B]

RHCP LHCP 19.01 dB

-90 -60 -30 0 30 60 90-50

-40

-30

-20

-10

0

XZ Plane

Angle [deg]

No

rmal

ized

Rad

iati

on

Pat

tern

[d

B]

RHCP LHCP 19.01 dB

-5 -4 -3 -2 -1 0 1 2 3 4 5-20

-15

-10

-5

0

XZ Plane

Angle [deg]

No

rmal

ized

Rad

iati

on P

atte

rn [

dB

]

9.57 GHz 9.65 GHz 9.73 GHz

-5 -4 -3 -2 -1 0 1 2 3 4 5-20

-15

-10

-5

0

YZ Plane

Angle [deg]

Norm

aliz

ed R

adia

tion P

att

ern [

dB

]

9.57 GHz 9.65 GHz 9.73 GHz

9.6 9.65 9.7-40

-35

-30

-25

-20

-15

-10

-5

0

Frequency (GHz)

S

[d

B]

One dim. radiating slot array (simulation) Feeder of one antenna panel (simulation) Fabricated antenna (measurement)

112

9.6 9.65 9.731

32

33

34

35

36

37

0

1

2

3

Frequency (GHz)

Dir

ect

ivit

y,

Gai

n (

dB

ic)

30%

40%

50%

60%

70%

80%

Directivity without back panel Directivity with back panel Gain (5.82 m) with back panel Gain (16.85 m) with back panel Axial ratio (16.85 m) with back panel

Ax

ial Ratio

(dB

)

1.6 dB0.02 GHz

0 10 20 30 40 50 608

10

12

14

16

-160

-140

-120

-100

-80

-60

-40

-20

0

[mm]

Coupling Factor (%)

Rad

iati

ng s

lot

len

gth

[m

m]

Phase

[deg

]

rl

[deg]

[deg]

S21

S31

Coupling slot Design

Radiating slot Design

Honeycomb core properties

,2

2

rc

=

π

βλε 0

εεεεrc = 1.06

z

y

x

z

y

x

Near Field Measurement

Amplitude

Phase

Aperture Distribution

Antenna Pattern

• The TE10 mode wave propagates in the

feeder to y direction.• Then the wave in the feeder is coupled to

the parallel plate by the coupling slots.

• The coupled wave travels in the parallel

plate to x direction.• Then this wave is coupled to z direction by

the radiating slots and becomes the

radiated wave.

Beam Shift

In the feeder, wave travel only to

positive y direction

Beam Shift

In the parallel-plate, wave travel

only to positive x direction

Input

Results of single coupling slot

simulation are used in the design of

feeder of one antenna panel.

Spacing of coupling slots are adjusted to

obtain optimum in-phase excitation (in

final the average spacing ≈≈≈≈ 1.03 λλλλf ).

Short

Results of one radiating

slot pair simulation are

used in the design of one

dimensional array of

radiating slot.

Spacing of radiating slot pair are

adjusted to obtain optimum in-phase

excitation (in final the average spacing ≈≈≈≈

0.9 λλλλ0 ).

Input Short

The measured antenna directivity, gain and axial

ratio. Here, adjustment factor equals to 1.7 dB and

0.08 dB are added to the antenna gain that

measured in 5.82 m and 16.85 m distance,

respectively.

(5.82 m and 16.85 m)

102 103 104 105

-20

-10

0

Precise Solution Far Field Estimation

E-F

ield

In

ten

sity

[d

B]

Distance [mm]

Adjustment

factor

0 10 20 30 40 500

5

10

15

20

-125

-100

-75

-50

-25

0

25

50

Coupling Factor [%]

[mm

]

[deg

]

γ [deg] [mm]

[mm]

[mm]

Sl

ip

il

[deg]

[deg]

arg.S21

arg.S31

Far Field Measurement

[Inner field measurement]

[Honeycomb inserted

in the WR90]

0 100 200 300 400 500 600-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

Travelling Distance (mm)

Loss

(dB

)

α = 0.0023 dB/mm

4.1 mm height of honeycomb 8.2 mm height of honeycomb

9.65 GHz

,4 eqwall εε

λ

−= 0

wh

( )( ).

tt2

tt2

rgcrcg

rgrccg

eqεε

εεε

+

+=

εεεεrg = adhesive permittivity

εεεεrc = honeycomb permittivity

εεεεwall = hardwall permittivity

λλλλ0 = free space wavelength

This document is provided by JAXA.